The present study on the separate and the combined effects of cigarette smoking and alcohol consumption on behavioral, electrocortical and cardiovascular functions involved 20 young female smokers, repeatedly tested on their performance in a visual information processing task before and after drug treatment. Each subject participated in four sessions where they received in a balanced sequence 0.7 g/kg alcohol or placebo followed by either real or sham smoking of a cigarette. The mental task required the subjects to detect sequences of three odd or even digits in a pseudorandom series of single digits presented on a TV screen. By using a variable subject-paced interstimulus interval, mental performance was analyzed continuously in terms of the achieved processing rate. The multivariate assessment of psychophysiological functions included the electrocardiogram, the finger plethysmogram and the electroencephalogram (EEG) measured on four electrode locations (Fz, Cz, P3, P4). The EEG was analyzed both for tonical changes in frequency distribution and for phasic responses to the correctly detected triads (Event-Related Potentials, ERP), yielding a CNV after the second digit and a late positive wave (LP) after the third digit. Cigarette smoking increased the processing rate, while it was decreased by alcohol. Smoking after alcohol diminished the performance decline due to alcohol. Heart rate acceleration and peripheral vasoconstriction were observed after smoking. Alcohol caused dilatation of the finger vessels which was prevented by smoking a cigarette after the drink.(ABSTRACT TRUNCATED AT 250 WORDS)